Primary liver cancer is the fifth most common cancer worldwide with approximately half a million cases reported in 1990. Hepatocellular carcinoma (HCC) accounts for 80% of all liver cancer and the rates of HCC have increased by over 70% in the last two decades in the U.S. The fatality ratio (mortality/incidence) of liver cancer is approximately 1, indicating that the majority of patients live less than a year. Late diagnosis due to lack of clinical symptoms is one of the main reasons for the high fatality ratio.
Liver cancer can result from both viral infection and chemical exposure. Known risk factors include hepatitis B and C virus infection and exposure to aflatoxin β1. It is not known whether distinct routes to liver cancer affect the same or different cellular pathways. No mutational model has yet been developed for liver cancer as it has been for other cancers such as colon cancer. The molecular events that precede neoplastic transformation of the liver are not well understood. With no clearly identified cause, successful treatment options are lacking. In fact, the specific genes that are deregulated in liver cancer have not yet been enumerated. This is a critical first step in developing a successful strategy for treating liver cancer.
There is a pressing need to understand the molecular events associated with the development of liver cancer, both in humans and in animal model systems where liver cancer is extensively studied, and to provide diagnostic and therapeutic reagents for treating same.